Marcus Thelen studied biochemistry at the University of Tübingen (DE) and received his PhD from the University of Bern in 1985. As postdoc at the Theodor-Kocher-Institute in Bern, his interests focused on inflammation and chemokines. In 1989, he went to the Rockefeller University in New York, joining the group of Alan Aderem in the Laboratory of Cellular Physiology and Immunology of the Cohn/Steinman department. Biochemical aspects of cytokine- and endotoxin-mediated phagocyte priming and cytoskeleton-mediated signal transduction were the topics of his studies. In 1992, he received a career development award (START) from the Swiss National Science Foundation and returned to the Theodor-Kocher-Institute at the University of Bern. He created his own research group working on molecular mechanisms of signal transduction in leukocytes, focusing on PI 3-kinase-dependent pathways and chemokine-mediated receptor activation. He obtained the venia docendi in 1994 and received an honorary professorship in 2001 from the University of Bern. In 2000 he moved to Bellinzona, where he helped open the IRB and directed the Signal Transduction Laboratory. Marcus Thelen retired in November 2022 and is currently working as a scientific advisor.